/*
SHA-1 in C
By Steve Reid <steve@edmweb.com>
100% Public Domain

Test Vectors (from FIPS PUB 180-1)
"abc"
  A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D
"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
  84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1
A million repetitions of "a"
  34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F
*/

/* #define LITTLE_ENDIAN * This should be #define'd already, if true. */
/* #define SHA1HANDSOFF * Copies data before messing with it. */

#define SHA1HANDSOFF

#include "sha1.h"
#include <stdio.h>
#include <string.h>
#include <sys/types.h> /* for u_int*_t */

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/* blk0() and blk() perform the initial expand. */
/* I got the idea of expanding during the round function from SSLeay */
/* BIG_ENDIAN defined by cmake TestBigEndian */
#ifndef BIG_ENDIAN
#define blk0(i)                                                                \
  (block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) |                         \
                 (rol(block->l[i], 8) & 0x00FF00FF))
#else
#define blk0(i)  block->l[i]
#endif

#define blk(i)                                                                 \
  (block->l[i & 15] = rol(block->l[(i + 13) & 15] ^ block->l[(i + 8) & 15] ^   \
                              block->l[(i + 2) & 15] ^ block->l[i & 15],       \
                          1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define R0(v, w, x, y, z, i)                                                   \
  z += ((w & (x ^ y)) ^ y) + blk0(i) + 0x5A827999 + rol(v, 5);                 \
  w = rol(w, 30);
#define R1(v, w, x, y, z, i)                                                   \
  z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5);                  \
  w = rol(w, 30);
#define R2(v, w, x, y, z, i)                                                   \
  z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5);                          \
  w = rol(w, 30);
#define R3(v, w, x, y, z, i)                                                   \
  z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5);            \
  w = rol(w, 30);
#define R4(v, w, x, y, z, i)                                                   \
  z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5);                          \
  w = rol(w, 30);

/* Hash a single 512-bit block. This is the core of the algorithm. */

void SHA1_Transform(uint32_t state[5], const uint8_t buffer[64]) {
  uint32_t a, b, c, d, e;
  typedef union {
    uint8_t c[64];
    uint32_t l[16];
  } CHAR64LONG16;
#ifdef SHA1HANDSOFF
  CHAR64LONG16 block[1]; /* use array to appear as a pointer */
  memcpy(block, buffer, 64);
#else
  /* The following had better never be used because it causes the
   * pointer-to-const buffer to be cast into a pointer to non-const.
   * And the result is written through.  I threw a "const" in, hoping
   * this will cause a diagnostic.
   */
  const CHAR64LONG16 *block = (const CHAR64LONG16 *)buffer;
#endif
  /* Copy context->state[] to working vars */
  a = state[0];
  b = state[1];
  c = state[2];
  d = state[3];
  e = state[4];
  /* 4 rounds of 20 operations each. Loop unrolled. */
  R0(a, b, c, d, e, 0);
  R0(e, a, b, c, d, 1);
  R0(d, e, a, b, c, 2);
  R0(c, d, e, a, b, 3);
  R0(b, c, d, e, a, 4);
  R0(a, b, c, d, e, 5);
  R0(e, a, b, c, d, 6);
  R0(d, e, a, b, c, 7);
  R0(c, d, e, a, b, 8);
  R0(b, c, d, e, a, 9);
  R0(a, b, c, d, e, 10);
  R0(e, a, b, c, d, 11);
  R0(d, e, a, b, c, 12);
  R0(c, d, e, a, b, 13);
  R0(b, c, d, e, a, 14);
  R0(a, b, c, d, e, 15);
  R1(e, a, b, c, d, 16);
  R1(d, e, a, b, c, 17);
  R1(c, d, e, a, b, 18);
  R1(b, c, d, e, a, 19);
  R2(a, b, c, d, e, 20);
  R2(e, a, b, c, d, 21);
  R2(d, e, a, b, c, 22);
  R2(c, d, e, a, b, 23);
  R2(b, c, d, e, a, 24);
  R2(a, b, c, d, e, 25);
  R2(e, a, b, c, d, 26);
  R2(d, e, a, b, c, 27);
  R2(c, d, e, a, b, 28);
  R2(b, c, d, e, a, 29);
  R2(a, b, c, d, e, 30);
  R2(e, a, b, c, d, 31);
  R2(d, e, a, b, c, 32);
  R2(c, d, e, a, b, 33);
  R2(b, c, d, e, a, 34);
  R2(a, b, c, d, e, 35);
  R2(e, a, b, c, d, 36);
  R2(d, e, a, b, c, 37);
  R2(c, d, e, a, b, 38);
  R2(b, c, d, e, a, 39);
  R3(a, b, c, d, e, 40);
  R3(e, a, b, c, d, 41);
  R3(d, e, a, b, c, 42);
  R3(c, d, e, a, b, 43);
  R3(b, c, d, e, a, 44);
  R3(a, b, c, d, e, 45);
  R3(e, a, b, c, d, 46);
  R3(d, e, a, b, c, 47);
  R3(c, d, e, a, b, 48);
  R3(b, c, d, e, a, 49);
  R3(a, b, c, d, e, 50);
  R3(e, a, b, c, d, 51);
  R3(d, e, a, b, c, 52);
  R3(c, d, e, a, b, 53);
  R3(b, c, d, e, a, 54);
  R3(a, b, c, d, e, 55);
  R3(e, a, b, c, d, 56);
  R3(d, e, a, b, c, 57);
  R3(c, d, e, a, b, 58);
  R3(b, c, d, e, a, 59);
  R4(a, b, c, d, e, 60);
  R4(e, a, b, c, d, 61);
  R4(d, e, a, b, c, 62);
  R4(c, d, e, a, b, 63);
  R4(b, c, d, e, a, 64);
  R4(a, b, c, d, e, 65);
  R4(e, a, b, c, d, 66);
  R4(d, e, a, b, c, 67);
  R4(c, d, e, a, b, 68);
  R4(b, c, d, e, a, 69);
  R4(a, b, c, d, e, 70);
  R4(e, a, b, c, d, 71);
  R4(d, e, a, b, c, 72);
  R4(c, d, e, a, b, 73);
  R4(b, c, d, e, a, 74);
  R4(a, b, c, d, e, 75);
  R4(e, a, b, c, d, 76);
  R4(d, e, a, b, c, 77);
  R4(c, d, e, a, b, 78);
  R4(b, c, d, e, a, 79);
  /* Add the working vars back into context.state[] */
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
  state[4] += e;
  /* Wipe variables */
  a = b = c = d = e = 0;
#ifdef SHA1HANDSOFF
  memset(block, '\0', sizeof(block));
#endif
}

/* SHA1_Init - Initialize new context */

void SHA1_Init(SHA1_CTX *context) {
  /* SHA1 initialization constants */
  context->state[0] = 0x67452301;
  context->state[1] = 0xEFCDAB89;
  context->state[2] = 0x98BADCFE;
  context->state[3] = 0x10325476;
  context->state[4] = 0xC3D2E1F0;
  context->count[0] = context->count[1] = 0;
}

/* Run your data through this. */

void SHA1_Update(SHA1_CTX *context, const uint8_t *data, const size_t len) {
  size_t i, j;

  j = context->count[0];
  if ((context->count[0] += len << 3) < j)
    context->count[1]++;
  context->count[1] += (len >> 29);
  j = (j >> 3) & 63;
  if ((j + len) > 63) {
    memcpy(&context->buffer[j], data, (i = 64 - j));
    SHA1_Transform(context->state, context->buffer);
    for (; i + 63 < len; i += 64) {
      SHA1_Transform(context->state, &data[i]);
    }
    j = 0;
  } else
    i = 0;
  memcpy(&context->buffer[j], &data[i], len - i);
}

/* Add padding and return len bytes of the message digest. */

void SHA1_Final(SHA1_CTX *context, unsigned len, uint8_t digest[SHA1_DIGEST_SIZE]) {
  unsigned i;
  uint8_t finalcount[8];
  uint8_t c;

  for (i = 0; i < 8; i++) {
    finalcount[i] =
        /* Endian independent */
        (uint8_t)(context->count[(i >= 4 ? 0 : 1)] >> ((3 - (i & 3)) * 8));
  }
  c = 0200;
  SHA1_Update(context, &c, 1);
  while ((context->count[0] & 504) != 448) {
    c = 0000;
    SHA1_Update(context, &c, 1);
  }
  SHA1_Update(context, finalcount, 8); /* Should cause a SHA1_Transform() */
  if (len > 20) {
      len = 20;
  }
  for (i = 0; i < len; i++) {
    digest[i] = (uint8_t)(context->state[i >> 2] >> ((3 - (i & 3)) * 8));
  }
  /* Wipe variables */
  memset(context, '\0', sizeof(*context));
  memset(&finalcount, '\0', sizeof(finalcount));
}

//-----------------------------------------------------------------------------
// self test

//#define TEST

#ifdef TEST

static const char *const test_data[] = {
    "abc", "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
    "A million repetitions of 'a'"};
static const char *const test_results[] = {
    "A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D",
    "84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1",
    "34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F"};

void digest_to_hex(const uint8_t digest[SHA1_DIGEST_SIZE], char *output) {
  int i, j;
  char *c = output;

  for (i = 0; i < SHA1_DIGEST_SIZE / 4; i++) {
    for (j = 0; j < 4; j++) {
      sprintf(c, "%02X", digest[i * 4 + j]);
      c += 2;
    }
    sprintf(c, " ");
    c += 1;
  }
  *(c - 1) = '\0';
}

int main(int argc, char **argv) {
  int k;
  SHA1_CTX context;
  uint8_t digest[20];
  char output[80];

  fprintf(stdout, "verifying SHA-1 implementation... ");

  for (k = 0; k < 2; k++) {
    SHA1_Init(&context);
    SHA1_Update(&context, (uint8_t *)test_data[k], strlen(test_data[k]));
    SHA1_Final(&context, digest);
    digest_to_hex(digest, output);

    if (strcmp(output, test_results[k])) {
      fprintf(stdout, "FAIL\n");
      fprintf(stderr, "* hash of \"%s\" incorrect:\n", test_data[k]);
      fprintf(stderr, "\t%s returned\n", output);
      fprintf(stderr, "\t%s is correct\n", test_results[k]);
      return (1);
    }
  }
  /* million 'a' vector we feed separately */
  SHA1_Init(&context);
  for (k = 0; k < 1000000; k++)
    SHA1_Update(&context, (uint8_t *)"a", 1);
  SHA1_Final(&context, digest);
  digest_to_hex(digest, output);
  if (strcmp(output, test_results[2])) {
    fprintf(stdout, "FAIL\n");
    fprintf(stderr, "* hash of \"%s\" incorrect:\n", test_data[2]);
    fprintf(stderr, "\t%s returned\n", output);
    fprintf(stderr, "\t%s is correct\n", test_results[2]);
    return (1);
  }

  /* success */
  fprintf(stdout, "ok\n");
  return (0);
}
#endif /* TEST */
